Definition

<Feature Face> instances have the following relationship with <Feature Volume> instances.

1. At any feature topology level, if a <Feature Face> instance FF associates to a <Feature Volume> instance FV, FV shall have a <Feature Volume Shell> component that associates to FF.

2. Conversely, if a <Feature Volume> instance FV has a <Feature Volume Shell> instance that associates to a <Feature Face> instance FF, FF shall also associate to FV.

<Geometry Face> instances have the following relationship with <Geometry Volume> instances. At any geometry topology level, if a <Geometry Face> instance GF associates to a <Geometry Volume> instance GV, GV shall also associate to GF. Conversely, if a <Geometry Volume> instance GV associates to a <Geometry Face> instance GF, GF shall also associate to GV.

Rationale

The associations between <Feature Face> and <Feature Volume> implement a boundary/co-boundary relationship. This topological relationship must be consistent, and must be consistent with the geometric representation of these objects.

The associations between <Geometry Face> and <Geometry Volume> implement a boundary/co-boundary relationship. A <Geometry Volume> instance is bounded by one or more <Geometry Face> instances. This topological relationship must be consistent, and must also be consistent with the geometric counterparts of these objects.

Example

1. A <Feature Volume> instance V1 representing a cube is bounded by six <Feature Face> instances F1 through F6. V1 is associated to F1, F2, F3, F4, F5, and F6 via its exterior <Feature Volume Shell> instance. Also, F1, F2, F3, F4, F5, and F6 are all associated to V1.

2. A <Geometry Volume> instance V1 representing a cube is bounded by six <Geometry Face> instances F1 through F6. V1 is associated to F1, F2, F3, F4, F5, and F6. Also, F1, F2, F3, F4, F5, and F6 are all associated to V1.

FAQs

Can a <Feature Face> instance be associated with a <Feature Volume> instance more than once?

Yes. A <Feature Face> instance that "dangles" into the interior of a <Feature Volume> instance FV will appear twice in the collection of <Feature Face> instances that are associated with the exterior <Feature Volume Shell> instance of FV, once with each orientation.

Can a <Geometry Face> instance be associated with a <Geometry Volume> instance more than once?

Yes. A <Geometry Face> instance that "dangles" into the interior of a <Geometry Volume> instance GV will appear twice in the collection of <Geometry Face> instances that are associated with GV, once with each orientation.